The truck can be found in San Francisco. There's a Volvo truck dealership and that's where the Tesla appears. Mind you, when you go to buy the truck, just click on the City of San Francisco and you'll see the Volvo dealership.

2018-12-12 22:38:08emsqueek (Guest)

Truck not showing up in any dealership.
Had this same issue when I tried the bus mods.
What am I doing wrong???